A majority of parts manufactured by forming are still made of a single material. A typical example related to the use of steel is a hot closed-die forging process, wherein steel stock is heated to the forming temperature, transferred to a forging die and deformed consecutively at individual stations of the progressive die so that it fills the die cavities. This forging is then trimmed, sized and cooled or subsequently heat treated. Where advanced high strength (AHS) steels are used, the microstructure must be modified by heat treatment of thermomechanical processing in order to obtain final martensitic microstructure with retained austenite. This process requires rapid cooling from the austenite temperature to a region between the Ms and Mf temperatures. The cooling is interrupted within the said temperature interval and followed by isothermal holding, which is necessary for stabilizing retained austenite at a temperature which is typically somewhat higher than the temperature at which quenching was interrupted. Within several minutes, the retained austenite is stabilized by carbon diffusion, which provides the steel with high strength and good ductility. In this processing method, it is necessary to interrupt cooling at a particular temperature which is relatively demanding to accomplish in practice. Formed parts of this kind can be manufactured from sheet stock by deep drawing followed by heat treatment of the aforementioned type. The resulting part shows high strength and, thanks to its structural configuration, sustains high loads up to the moment when it becomes unstable and, consequently, destroyed. The destruction takes the form of a collapse of the part's structure due to overload. If solid material is used, the structure does not tend to collapse equally easily but there is a disadvantage of the relatively high weight of such part and of higher manufacturing cost of the formed part.
For instance, the known document no. CA 02759154 describes synthetizing of high-thermal-conductivity hybrid materials from two groups of metallic materials: the first group comprises aluminium, magnesium and zirconium alloys and the other contains stainless, carbon or tool steels and nickel and titanium alloys. The base materials from the first group exhibit much higher thermal conductivity than the base materials from the second group. The hybrid materials contain a layer of oxides based on these metallic elements. These oxides are synthetized using plasma oxidation, as described in the document no. CA 2556869.